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The Single UNIX &reg; Specification, Version 2<br>
Copyright &copy; 1997 The Open Group

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<h4><a name = "tag_000_005_257">&nbsp;</a>NAME</h4><blockquote>
frexp - extract mantissa and exponent from a double precision number
</blockquote><h4><a name = "tag_000_005_258">&nbsp;</a>SYNOPSIS</h4><blockquote>
<pre><code>

#include &lt;<a href="math.h.html">math.h</a>&gt;

double frexp(double <i>num</i>, int *<i>exp</i>);
</code>
</pre>
</blockquote><h4><a name = "tag_000_005_259">&nbsp;</a>DESCRIPTION</h4><blockquote>
The
<i>frexp()</i>
function breaks a floating-point number into a normalised
fraction and an integral power of 2.
It stores the integer exponent in the
<b>int</b>
object pointed to by
<i>exp</i>.
<p>
An application wishing to check for error situations should set
<i>errno</i>
to 0 before calling
<i>frexp()</i>.
If
<i>errno</i>
is non-zero on return, or the return value is NaN, an error has occurred.
</blockquote><h4><a name = "tag_000_005_260">&nbsp;</a>RETURN VALUE</h4><blockquote>
The
<i>frexp()</i>
function returns the value
<i>x</i>,
such that
<i>x</i>
is a
<b>double</b>
with magnitude in the interval [&frac12;, 1) or 0, and
<i>num</i>
equals
<i>x</i>
times 2 raised to the power
<i>*exp</i>.
<p>
If
<i>num</i>
is 0, both parts of the result are 0.
<p>
If
<i>num</i>
is NaN, NaN is returned,
<i>errno</i>
may be set to [EDOM] and the value of
<i>*exp</i>
is unspecified.
<p>
If
<i>num</i>
is &plusmn;Inf,
<i>num</i>
is returned,
<i>errno</i>
may be set to [EDOM] and the value of
<i>*exp</i>
is unspecified.
</blockquote><h4><a name = "tag_000_005_261">&nbsp;</a>ERRORS</h4><blockquote>
The
<i>frexp()</i>
function may fail if:
<dl compact>

<dt>[EDOM]<dd>
The value of
<i>num</i>
is NaN or &plusmn;Inf.

</dl>
<p>
No other errors will occur.
</blockquote><h4><a name = "tag_000_005_262">&nbsp;</a>EXAMPLES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_005_263">&nbsp;</a>APPLICATION USAGE</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_005_264">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_005_265">&nbsp;</a>SEE ALSO</h4><blockquote>
<i><a href="isnan.html">isnan()</a></i>,
<i><a href="ldexp.html">ldexp()</a></i>,
<i><a href="modf.html">modf()</a></i>,
<i><a href="math.h.html">&lt;math.h&gt;</a></i>.
</blockquote><h4>DERIVATION</h4><blockquote>
Derived from Issue 1 of the SVID.
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UNIX &reg; is a registered Trademark of The Open Group.<br>
Copyright &copy; 1997 The Open Group
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